There were periods of time during the whaling years when war was a particular threat to sailors. During the Revolutionary War, many whaling ships were commissioned by the American army as privateers. To defend against themselves, the British attacked any whale port that gave shelter to the privateers and as a result over 1200 whalemen were killed or imprisoned by the British and 134 whaling ships were seized. Thirty years later, war interrupted the whaling industry again when the British began seizing American ships and forcing sailors into the British navy to fight against the French in the War of 1812. This went on for two years until a treaty was signed and the ships and sailors were freed. Later, during the Civil War the Confederate raiders Alabama and Shenandoah burnt and sank over 30 ships.